DEA-C01 Data Store Management Practice Question
Network Topology
Refer to the exhibit. A data engineer needs to connect to the Redshift cluster from an EC2 instance in the same VPC. The engineer can ping the EC2 instance but cannot connect to Redshift using the endpoint address and port 5439. What is the most likely cause?
⚠ Common exam trap
AWS often tests the distinction between ICMP reachability (ping) and TCP port-level connectivity, leading candidates to overlook security group rules when they see successful ping results.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The security group for the Redshift cluster does not allow inbound traffic on port 5439 from the EC2 instance.
The most likely cause is that the security group associated with the Redshift cluster does not have an inbound rule allowing TCP traffic on port 5439 from the security group or IP address of the EC2 instance. Since the engineer can ping the EC2 instance (ICMP works), but cannot connect to Redshift on port 5439, this points to a firewall or security group rule blocking the specific port, not a network reachability issue.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The security group for the Redshift cluster does not allow inbound traffic on port 5439 from the EC2 instance.
Why this is correct
Reachability via ping only proves ICMP is permitted; Redshift listens on TCP 5439, so the cluster's security group must allow inbound 5439 from the EC2 instance's security group or private IP. Without that rule, the endpoint connection times out.
- ✗
The Redshift cluster is in a different VPC.
Why it's wrong here
The stem states both resources are in the same VPC, so cross-VPC peering or transit gateway configuration cannot be the cause. It is tempting because differing VPCs commonly break connectivity, and would be correct if the EC2 instance and cluster genuinely resided in separate VPCs without peering.
- ✗
The Redshift cluster is not in an available state.
Why it's wrong here
Cluster state affects availability, but the exhibit shows the endpoint resolving and the security group blocking port 5439, which is the actual fault. It is tempting because an unavailable cluster does refuse connections, and would be correct if the console showed the cluster paused, resizing or otherwise not available.
- ✗
The Redshift cluster is publicly accessible and requires an internet gateway.
Why it's wrong here
Public accessibility is irrelevant here: the EC2 instance sits in the same VPC, so traffic to Redshift stays on private addressing and never traverses an internet gateway. It is tempting because public clusters do need gateway routing, and would be correct if the client were outside the VPC reaching a publicly accessible endpoint.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DEA-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DEA-C01 exam.